﻿/*************************************************************************************************
  Required Notice: Copyright (C) EPPlus Software AB. 
  This software is licensed under PolyForm Noncommercial License 1.0.0 
  and may only be used for noncommercial purposes 
  https://polyformproject.org/licenses/noncommercial/1.0.0/

  A commercial license to use this software can be purchased at https://epplussoftware.com
 *************************************************************************************************
  Date               Author                       Change
 *************************************************************************************************
  01/27/2020         EPPlus Software AB       Initial release EPPlus 5
 *************************************************************************************************/
using System;
using System.Collections.Generic;
using System.Text;

namespace OfficeOpenXml.FormulaParsing.Excel.Functions.Math.RomanFunctions
{
    internal abstract class RomanBase
    {
        protected class RomanNumber
        {
            public RomanNumber(int number, string letter)
            {
                Number = number;
                Letter = letter;
            }
            public int Number { get; set; }

            public string Letter { get; set; }
        }

        protected readonly RomanNumber One = new RomanNumber(1, "I");
        protected readonly RomanNumber Five = new RomanNumber(5, "V");
        protected readonly RomanNumber Ten = new RomanNumber(10, "X");
        protected readonly RomanNumber Fifty = new RomanNumber(50, "L");
        protected readonly RomanNumber OneHundred = new RomanNumber(100, "C");
        protected readonly RomanNumber FiveHundred = new RomanNumber(500, "D");
        protected readonly RomanNumber Thousand = new RomanNumber(1000, "M");

        internal abstract string Execute(int number);

        protected string GetClassicRomanFormat(int number)
        {
            var roman = new StringBuilder();
            Apply(ref number, Thousand, roman);
            Apply(ref number, 900, "CM", roman);
            Apply(ref number, FiveHundred, OneHundred, roman);
            Apply(ref number, 400, "CD", roman);
            Apply(ref number, OneHundred, roman);
            Apply(ref number, 90, "XC", roman);
            Apply(ref number, Fifty, Ten, roman);
            Apply(ref number, 40, "XL", roman);
            Apply(ref number, Ten, roman);
            Apply(ref number, 9, "IX", roman);
            Apply(ref number, Five, One, roman);
            Apply(ref number, 4, "IV", roman);
            Apply(ref number, One, roman);
            return roman.ToString();
        }

        private void Apply(ref int number, RomanNumber roman, StringBuilder result)
        {
            if (number >= roman.Number)
            {
                var limit = number / roman.Number;
                for (var x = 0; x < limit; x++)
                {
                    result.Append(roman.Letter);
                    number -= roman.Number;
                }
            }
        }

        private void Apply(ref int number, RomanNumber roman, RomanNumber lowerRoman, StringBuilder result)
        {
            if (number >= roman.Number)
            {
                result.Append(roman.Letter);
                number -= roman.Number;
                var limit = number / lowerRoman.Number;
                for (var x = 0; x < (number / lowerRoman.Number); x++)
                {
                    result.Append(lowerRoman.Letter);
                    number -= lowerRoman.Number;
                }
            }
        }

        private void Apply(ref int number, int limit, string letters, StringBuilder result)
        {
            if (number >= limit)
            {
                result.Append(letters);
                number -= limit;
            }
        }

        protected string HandleType(int type, string roman)
        {
            if (type <= 0) return roman;

            // all other types than 0
            roman = roman.Replace("CMXCV", "LMVL");
            roman = roman.Replace("CML", "LM");
            roman = roman.Replace("CDL", "LD");
            roman = roman.Replace("XCV", "VC");
            roman = roman.Replace("XLV", "VL");
            
            // type 1
            if(type == 1)
            {
                roman = roman.Replace("XLIX", "VLIV");
                roman = roman.Replace("XCIX", "VCIV");
                roman = roman.Replace("CMXC", "LMXL");
                roman = roman.Replace("CDVC", "LDVL");
                roman = roman.Replace("CDXC", "LDXL");
            }
            if(type > 1)
            {
                roman = roman.Replace("XLIX", "IL");
                roman = roman.Replace("XCIX", "IC");
                roman = roman.Replace("CDXC", "XD");
                roman = roman.Replace("CDVC", "XDV");
                roman = roman.Replace("CDIC", "XDIX");
                roman = roman.Replace("LMVL", "XMV");
                roman = roman.Replace("CMIC", "XMIX");
                roman = roman.Replace("CMXC", "XM");
            }
            if(type > 2)
            {
                roman = roman.Replace("XDV", "VD");
                roman = roman.Replace("XDIX", "VDIV");
                roman = roman.Replace("XMV", "VM");
                roman = roman.Replace("XMIX", "VMIV");
            }
            if(type == 4)
            {
                roman = roman.Replace("VDIV", "ID");
                roman = roman.Replace("VMIV", "IM");
            }
            return roman;
        }
    }
}
